The present invention is directed generally to spectrofluorometric systems, and more particularly to a system and apparatus for generating a contour plot of the total luminescence spectrum of a sample material.
Fluorescence spectroscopy, because of its high degree of sensitivity and specificity, has proven useful in many different fields for chemical identification of unknown substances. One field where this process has been particularly useful is in the field of environmental protection for tracing the source of water pollutants. Many types of water polluting material, such as oil spills, include naturally fluorescing components, such as polynuclear aeromatic hydrocarbons, which are particularly volatile or soluable and are therefore relatively stable to weathering. These components can be positively identified, or fingerprinted, even after a period of time in water.
To provide an identification, or fingerprint, of greater specificity, it has been proposed that the fluorescence intensity of a unknown sample be plotted as contours of equal amplitude against both excitation and emission wavelengths. Prior art methods and apparatus for generating such plots have either relied on computer analysis of fluorescence data collected at various wavelengths, requiring the use of a mini-computer and associated peripheral equipment, or have relied on time-consuming manual data collection and plotting procedures. Neither of these has been entirely satisfactory for use in environmental protection operations because of time and equipment considerations.
The present invention is directed to a method and apparatus for generating a contour plot utilizing a spectrofluorometer and plotter of conventional design and construction and with a minimum of additional apparatus.